Ophthalmological device for treating eye tissue

ABSTRACT

An ophthalmological device (10) for treating eye tissue (6) with laser pulses (L) comprises a projection optical unit (3) for focused projection of the laser pulses (L), a scanner system (1) for dynamically deflecting the laser pulses (L) and a zoom system (20), which is arranged between the projection optical unit (3) and the scanner system (1) and which is configured to adjust the focused projection of the laser pulses (L) in the projection direction (r) in different zoom settings (z). The ophthalmological device (10) moreover comprises a displacement device (4), which is configured to displace the scanner system (1) depending on the zoom setting (z) of the zoom system (20). What the displacement (s) of the scanner system (1) coupled to the zoom setting (z) of the zoom system (20) renders possible is the adaptation of the position of the scanner system (1) in a dynamic and synchronized fashion to the setting of the zoom system (20) and hence to the current position of the virtual entry pupil (Pa, Pb) of the zoom system (20).

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims benefit of U.S. Provisional ApplicationNo. 61/753,141, filed Jan. 16, 2013, the disclosure of which isincorporated herein by reference.

TECHNICAL FIELD

The present invention relates to an ophthalmological device for treatingeye tissue with laser pulses. The present invention more particularlyrelates to an ophthalmological device for treating eye tissue with laserpulses, comprising a scanner system for dynamically deflecting the laserpulses and a projection optical unit for focused projection of the laserpulses.

PRIOR ART

When treating eye tissue with pulsed laser beams, use is made offocusing devices in order to adjust the focusing range. Particularly inthe case of ophthalmological laser systems with extended fields ofapplication, which, in addition to the treatment of eye tissue of thecornea, should enable focus positions extending beyond the cornea, e.g.for lens surgery or for the treatment of other eye regions situatedbehind the cornea, provision is made for focusing devices in the beampath between the laser source and the projection optical unit in orderto extend or adjust the focusing range. These focusing devices carry outzoom movements or zoom functions for adjusting the focus depth in theoptical path so that the focused projection is displaced in theprojection direction. The zoom movements or zoom functions comprise adisplacement of one or more optical elements along the optical axis of asystem. Considered in general, a zoom action can be carried out bydisplaceable lenses or mirrors, but also by other optical elements, forexample by deformable lenses, deformable mirrors, SLM (spatial lightmodulator) systems or systems with dynamic modulation of the refractiveindex. Hence general optical systems which adjust the focal lengththereof are considered to be zoom systems. Depending on the technicalimplementation, a different number of elements are required for this.Hence the focus position is determined by the zoom setting of the zoomsystem, with the zoom setting being determined, depending on thetechnical implementation, by zoom movements of lenses and/or mirrors orzoom actions or zoom functions for setting deformable lenses, deformablemirrors, SLM systems or refractive index modulators.

WO2011/017000 describes an optical system with a scanner system forophthalmological laser surgery, which comprises a zoom system whichenables a depth scan or z-scan beyond the region of the cornea down intothe depths of the lens, with the focus position being adjusted over anextended range from the cornea into the lens. In the optical system asper WO2011/017000, the position of the virtual entry pupil of the zoomsystem is modified by the zoom actions carried out during the depth scanor z-scan. Here, depending on the current setting of the zoom system,this causes increased distances of the scanner system from the virtualentry pupil of the zoom system. The upshot of this is that the zoomsystem must have a design with the larger diameter and hence it is moreexpensive (the costs increase at least with the square of the diameter).Furthermore, use has to be made of larger scanner systems, e.g. largermirrors, or other measures have to be taken so that the laser beamsdeflected by the scanner system can enter the entry pupil of the zoomsystem without restrictions. In accordance with WO2011/017000, twoadditional scanning axes are proposed to this end, which re-deflect thescanned beam onto the optical axis in such a way that, in every zoomposition, the deflected laser beam intersects the optical axes at thepoint where the current entry pupil of the zoom system is situated. Withthe interaction of the four scanner axes, it is possible, firstly, toset the deflection angle (scanning angle) in two spatial directions and,secondly, also to determine the point of intersection of the deflectedlaser beam with the optical axis. However, in this case, the advantageof a more compact optical system is bought by the disadvantage of asignificantly increased control complexity and additional scannersystems.

DESCRIPTION OF THE INVENTION

It is an object of the present invention to propose an ophthalmologicaldevice for treating eye tissue with laser pulses, which does not have atleast some of the disadvantages of the known systems. In particular, itis an object of the present invention to propose an ophthalmologicaldevice for treating eye tissue with laser pulses, which enables anadjustment of the focus position of the laser pulses in the projectiondirection, without having to provide enlarged and/or additional scannermirrors to this end or minimize the diameter and the size of the zoomsystem.

In accordance with the present invention, these goals are achieved bythe features of the independent claims. Further advantageous embodimentsmoreover emerge from the dependent claims and the description.

An ophthalmological device for treating eye tissue with laser pulsescomprises a scanner system for dynamically deflecting the laser pulses,a projection optical unit for focused projection of the laser pulses anda zoom system, which is arranged between the scanner system and theprojection optical unit and which is configured to adjust the focusedprojection of the laser pulses in the projection direction in differentzoom settings.

The aforementioned goals are, in particular, achieved by the presentinvention by virtue of the fact that the ophthalmological devicemoreover comprises a displacement device, which is configured todisplace the scanner system depending on the zoom setting of the zoomsystem.

A simple displacement movement of the scanner system, which is onlydependent on the zoom setting, i.e., for example, on the zoom movement,enables a significantly simpler connection of the scanner system to thezoom system than the solution of a synchronized movement of four mirroraxes described in the prior art. Compared to the prior art, it ispossible to save corresponding scanner systems for two mirror axes,which reduces the thermal load on the optical systems due to the scannerdrives, and there is no need to provide a control with closed-loopcontrol algorithms for a complex, four-axes scanner system. Moreover, itis also possible to reduce the instrument costs overall and higherdynamics (speed) can be achieved by the enabled use of small mirrors.

In a preferred embodiment variant, the displacement device is configuredto displace the scanner system along an optical axis of the zoom system.The displacement device preferably comprises a drive for displacing thescanner system.

In a further embodiment variant, the displacement device is configuredto displace the scanner system in a synchronized manner with the zoomsetting of the zoom system.

In one embodiment variant, the displacement device is configured todisplace the scanner system in a synchronized manner with the adjustmentof the focused projection brought about by the zoom system.

In a further embodiment variant, the displacement device is configuredto displace the scanner system depending on the position of a virtualentry pupil of the zoom system. In one embodiment variant, thedisplacement device is configured to displace the scanner system alongan optical axis of the zoom system to a defined position in respect ofthe virtual entry pupil of the zoom system. Hence, the whole scannersystem can be displaced along the optical axis using a simpletranslation in order to position the deflection mirrors as closely aspossible to or in the virtual entry pupil of the zoom system.

In a further embodiment variant, the ophthalmological device comprises acontrol module, which is configured to generate positioning signals forcontrolling a drive provided for displacing the scanner system,depending on control signals for the zoom system or on feedback signalsfrom the zoom system.

In one embodiment variant, the scanner system comprises a mirror whichis rigid in relation to the scanner system, also moved in the case of adisplacement of the scanner system and configured to guide the laserpulses from a laser source to a movable deflection mirror of the scannersystem.

In a further embodiment variant, the ophthalmological device comprisesan optical transmission system, which is interposed between the scannersystem and the zoom system and configured to transmit the laser pulsesdeflected by the scanner system to the zoom system. By way of example,the optical transmission system is arranged in a mechanical supportsystem, by means of which the scanner system and the zoom system aremechanically connected to one another.

In one embodiment variant, the ophthalmological device comprises anoptical transmission system, which is interposed between the zoom systemand the projection optical unit and configured to transmit the laserpulses from the zoom system to the projection optical unit. By way ofexample, the optical transmission system is arranged in a mechanicalsupport system, by means of which the projection optical unit and thezoom system are mechanically connected to one another.

In a further embodiment variant, the ophthalmological device comprises acompensation system, which is configured to optically compensateaberrations of the zoom system depending on displacement and deflectionangle of the scanner system.

By way of example, the ophthalmological device comprises a laser source,which is configured to generate femtosecond laser pulses. The scannersystem comprises at least one movable mirror for dynamically deflectingthe laser pulses. The projection optical unit is configured to projectthe laser pulses into the eye tissue in a focused manner in order tobreak down eye tissue.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following text, an embodiment of the present invention isdescribed on the basis of an example. The exemplary embodiment isillustrated by the following attached figures:

FIG. 1 schematically shows a cross section of an ophthalmological devicein accordance with the prior art for treating eye tissue with laserpulses, having a scanner system and a zoom system.

FIG. 2 schematically shows a cross section of an ophthalmological devicefor treating eye tissue with laser pulses, having a displacement devicefor displacing the scanner system depending on settings of the zoomsystem.

FIGS. 3-7 schematically show a cross section of different embodiments ofan ophthalmological device for treating eye tissue with laser pulses,having a displacement device for displacing the scanner system dependingon settings of the zoom system.

WAYS OF IMPLEMENTING THE INVENTION

In FIG. 1, reference sign 10′ relates to an ophthalmological device inaccordance with the prior art for treating eye tissue 6 with laserpulses L. The ophthalmological device 10′ comprises a laser source 100,a projection optical unit 3 for focused projection of the laser pulsesL, a scanner system 1′ for dynamically deflecting the laser pulses L anda focusing device 2 with an optical zoom system 20, which is arranged inthe beam path between the projection optical unit 3 and the scannersystem 1′ and which is configured to adjust the focused projection ofthe laser pulses L in projection direction r, depending on theschematically depicted zoom setting z of the zoom system 20, in order toset different focus depths A, B, as indicated by the focus adjustmentΔf.

By way of example, the zoom system 20 comprises several (typically two,but also three or four if, in addition to the focus position, otheroptical parameters such as beam divergence or focus diameter are also tobe set and/or if aberrations are to be compensated for) lenses and/orlens groups, which are displaceable along the optical axis q and whichare configured to modify and determine the zoom setting z of the zoomsystem 20 by zoom movements, in order thereby to adjust the focusedprojection of the laser pulses L in projection direction r and generatea focus adjustment Δf for different focus depths A, B. As mentioned atthe outset, the zoom system 20 can also comprise other optical elementsin addition to or instead of displaceable lenses in alternativeembodiments variants, for example mirrors, deformable lenses, deformablemirrors, SLM (spatial light modulator) systems or systems with dynamicmodulation of the refractive index, in order to modify and determine thezoom setting z of the zoom system 20 by means of corresponding zoomactions or zoom functions.

As depicted in FIGS. 1 to 7, the zoom system 20 is arranged between theprojection optical unit 3 and the scanner system 1, 1′. However, aperson skilled in the art will understand that, depending on theembodiment variant, the zoom system 20 can also have parts, e.g. lensesand/or lens groups, arranged upstream of the scanner system 1, 1′, i.e.arranged closer to the laser source 100 on the optical path.

The zoom system 20 has a changeable entry pupil Pa, Pb. The entry pupilPa, Pb of an optical system is an imagined, i.e. virtual, stop, whichrestricts the beams of the optical system. As can be seen from FIG. 1,the adjustment of the focused projection of the laser pulses L by thezoom system 20 brings about not only the focus adjustment Δf but also adisplacement s′ of the position of the (virtual) entry pupil Pa, Pb ofthe zoom system 20 along the optical axis q of the zoom system 20. Thisincreases the distance between the scanner system 1′ and the zoom system20, which (in the depicted example) makes an enlargement of the diameterof the zoom system 20 necessary and possibly also requires a largerscanner aperture of the scanner system 1′ (otherwise the scanning anglewould have to be reduced). What holds true in general is that thediameter of the zoom system 20 has to be enlarged if the scanneraperture does not coincide with the entry pupil of the zoom system 20(i.e. does not lie at the same location in the case where the diameteris the same). Otherwise the scanned beam is cut off on physical stops inthe zoom system 20, which is also known by the term vignetting. The beamprofiles in FIG. 1 only schematically depict the usable beam crosssections. A disadvantage when using a scanning mirror (with beamcoupling from the side) is also that only part of the radiated laserpower is transmitted. The effect that the size of the entry pupil Pa, Pbcan also change depending on the zoom system 20 was not depicted inFIG. 1. The relationships explained here show that an optimal design ofscanner and zoom with the goal of minimizing both the scanner aperturesand the diameter of the zoom system 20 cannot be realized by the use oftwo scanning axes as known in the prior art. Both an enlargement of thezoom system 20 and an enlargement of deflection mirrors are connectedwith increased costs and the disadvantages already described at theoutset.

In FIGS. 2 to 7, reference sign 10 relates to an ophthalmological devicefor treating eye tissue 6 with laser pulses L, which device, in contrastto the prior art, has a displacement device 4 in addition to lasersource 100, projection optical unit 3, scanner system 1 and focusingdevice 2 with optical zoom system 20, which displacement device isconfigured to displace the scanner system 1 along the optical axis q ofthe zoom system 20, as indicated by the displacement (translationalmovement) denoted by s.

The scanner system 1 comprises one or more deflection apparatuses, e.g.movable deflection mirrors, which are configured to deflect the laserpulses L dynamically in at least one deflection direction and therebyguide the laser beam formed by the laser pulses L along at least onescanning direction by modifying the deflection angle (scanning angle inrelation to the optical axis). Depending on the embodiment variant, thescanner system 1 comprises one or more galvanoscanners, polygonscanners, resonance scanners, AOM (acoustic-optic modulator) scanners,EOM (electro-optic modulator) scanners and/or SLM (spatial lightmodulator) scanners.

The laser source 100 is configured to generate a laser beam pulsed bylaser pulses L, e.g. by femtosecond laser pulses.

The displacement device 4 is configured, in particular, to displace thescanner system 1 dependent (i) on the current zoom setting z of the zoomsystem 20. That is to say, the displacement device 4 is configured todisplace the scanner system 1 coupled to (i) the zoom movement/zoomfunction carried out by the zoom system 20 or (ii) the displacement s ofthe virtual entry pupil Pa, Pb of the zoom system 20 brought about bythe zoom movement/zoom function or (iii) the focus adjustment Δf broughtabout by the zoom movement/zoom function.

As depicted schematically in FIGS. 2 to 7, the displacement device 4comprises a drive 41, coupled to the scanner system 1, for displacingthe scanner system 1. As depicted schematically in FIGS. 3 to 7, thedisplacement device 4 moreover comprises a control module 42, which isconfigured to control the drive 41 depending on the current zoom settingz of the zoom system 20, i.e. depending on the zoom movement/zoomfunction of the zoom system 20. The control module 42 comprises one ormore circuits, for example a processor with stored computer programcode, a programmed logic circuit and/or an electronic circuit, which isconfigured to control the drive 41 for displacing the scanner system 1depending on the current zoom setting z of the zoom system 20, i.e.depending on the zoom movement/zoom function of the zoom system 20. Tothis end, the control module 42 generates positioning signals p, whichare fed to the drive 41 of the displacement device 4 for carrying outthe displacement s. In one embodiment variant, the control module 42 isconfigured to generate the positioning signals p for the drive 41depending on focusing signals f, which are fed to the zoom system 20,for determining the current zoom setting z, by means of which a focusadjustment Δf for setting the desired projection focus in projectiondirection r is obtained. Here, the focusing signals f are generated inthe control module 42 itself or in another control unit, for example inthe focusing device 2, which is independent of the control module 42. Inan alternative embodiment, the zoom system 20 generates a feedbacksignal, which continuously provides the control module 42 with thecurrent zoom setting z. Accordingly, the control module 42 controls thedrive 41 depending on the feedback signal, which specifies the currentzoom setting z. By displacing s the scanner system 1 depending on thecurrent zoom setting z of the zoom system 20, it is possible to adaptthe position of the scanner system 1 in a dynamic and synchronizedfashion to the current position of the virtual entry pupil Pa, Pb of thezoom system 20. Here, the scanner system 1 or the deflection mirrorsthereof are continuously positioned as close as possible to the virtualentry pupil Pa, Pb of the zoom system 20, for example at a position witha fixedly defined distance value from the virtual entry pupil Pa, Pb ordirectly into the virtual entry pupil Pa, Pb. Furthermore, the scannerdisplacement can also occur in discrete steps. In the case of anteriorchamber surgery of cornea and lens at least two scanner positions wouldhave to be met for this purpose, one for the cornea and one for thelens.

The zoom system 20 optionally comprises a compensation system 21, whichis configured to optically compensate aberrations of the zoom system 20depending on the displacement s (and therefore implicitly also dependingon the current zoom setting z of the zoom system 20) and/or deflectionangle(s) of the scanner system 1. The compensation system 21 comprisesone or more circuits, for example a processor with stored computerprogram code, a programmed logic circuit and/or an electronic circuit,which are configured to control the zoom system 20 depending on thecurrent displacement s and the current deflection angle or angles of thescanner system 1 in such a way that aberrations of the zoom system 20are compensated for, which would be caused by the relevant displacements and the relevant deflection angle or angles of the scanner system 1.To this end, in one embodiment variant, the compensation system 21comprises a compensation table or compensation function, which in eachcase specifies correction values or compensated focusing signals f forcontrolling the zoom system 20 for various displacements s anddeflection angles of the scanner system 1. In another embodimentvariant, the displacement of the scanner system s itself is used tocompensate for aberrations.

As depicted schematically in FIGS. 1 to 7, the ophthalmological device10, 10′ comprises an optical transmission system 30, by means of whichthe laser pulses L are guided from the focusing device 2 or from thezoom system 20 to the projection optical unit 3.

As depicted schematically in FIGS. 4 to 7, the optical transmissionsystem 30 comprises, depending on the embodiment variant, an optionalsupport system 33 and an application head 32, wherein the opticalelements of the optical transmission system 30 are arranged in thesupport system 33 and/or in the application head 32 and the projectionoptical unit 3 is attached to the application head 32 or integrated intothe application head 32. Depending on the embodiment variant, theoptical elements of the optical transmission system 30 comprise one ormore mirrors for deflecting the laser beam or the laser pulses L and oneor more lenses, for example for generating one or more intermediatefocuses in the beam path between the focusing device 2 or the zoomsystem 20 and the projection optical unit 3. In a particularly simpleembodiment, the optical transmission system 30 comprises a deflectionmirror 31 as sole optical element. In various embodiment variants, thesupport system 33 comprises a rigid support arm, a multi-member, movablehinged arm or only a coupling system for fixed or detachable attachmentof the application head 32 on the focusing device 2.

As depicted schematically in FIG. 5, the optical transmission system 30comprises a further zoom system 21 in one embodiment variant, whichfurther zoom system is configured to adjust the focused projection ofthe laser pulses L in projection direction r in order to set differentfocus depths.

As depicted schematically in FIGS. 6 and 7, the ophthalmological device10 comprises a deflection mirror 12 in one embodiment variant, whichdeflection mirror is fixedly attached to the scanner system 1 andconfigured to be immobile in respect of the scanner system 1. By meansof this deflection mirror 12 of the scanner system 1, the laser pulses Lor the laser beam are fed from the laser source 100 to the scannersystem 1, in particular to a movable mirror of the scanner system 1.

As depicted schematically in FIG. 7, the ophthalmological device 10comprises a further optical transmission system 13 in one embodimentvariant, which optical transmission system is interposed in the beampath between the scanner system 1 and the focusing device 2 or the zoomsystem 20. Depending on the embodiment variant, the optical elements ofthis further optical transmission system 13 comprise one or more mirrorsfor deflecting the laser beam or the laser pulses L and/or one or morelenses, for example for generating one or more intermediate focuses inthe beam path between the scanner system 1 and the focusing device 2 orthe zoom system 20. By way of example, the further optical transmissionsystem 13 is arranged in a mechanical support system, which mechanicallyconnects the scanner system 1 and the zoom system 20 to one another.

The invention claimed is:
 1. An ophthalmological device for treating eyetissue with laser pulses, comprising: a scanner system for dynamicallydeflecting the laser pulses; a projection optical unit for focusedprojection of the laser pulses in a projection direction; a zoom system,which is arranged downstream of the scanner system and upstream of theprojection optical unit, between the scanner system and the projectionoptical unit, and which is configured to adjust the focused projectionof the laser pulses in the projection direction in different zoomsettings, whereby the zoom system has an optical axis and a virtualentry pupil which moves along the optical axis with the different zoomsettings; and a displacement device, which is configured to displace thescanner system along the optical axis of the zoom system depending onthe zoom setting of the zoom system, the displacement device comprisinga drive coupled to the scanner system and configured to displace thescanner system along the optical axis of the zoom system, and one ormore circuits configured to control the drive to displace the scannersystem along the optical axis of the zoom system using a current zoomsetting of the zoom system, wherein the displacement device isconfigured to adapt a position of the scanner system, with respect to acurrent position of the virtual entry pupil of the zoom system, forcontinuously maintaining a value of distance of the scanner system fromthe virtual entry pupil of the zoom system.
 2. The ophthalmologicaldevice as claimed in claim 1, wherein the one or more circuits areconfigured to control the drive to displace the scanner system dependingon the current position of the virtual entry pupil of the zoom system.3. The ophthalmological device as claimed in claim 1, wherein the one ormore circuits are configured to control the drive to displace thescanner system along the optical axis of the zoom system to a definedposition in respect of the virtual entry pupil of the zoom system.
 4. Anophthalmological device for treating eye tissue with laser pulses,comprising: a scanner system for dynamically deflecting the laserpulses; a projection optical unit for focused projection of the laserpulses in a projection direction; a zoom system, which is arrangeddownstream of the scanner system and upstream of the projection opticalunit, between the scanner system and the projection optical unit, andwhich has an optical axis and is configured to adjust the focusedprojection of the laser pulses in a projection direction in differentzoom settings, whereby the zoom system has a virtual entry pupil whichmoves along the optical axis with the different zoom settings; and adisplacement device, which is configured to displace the scanner system,along the optical axis of the zoom system and coupled to a zoom movementcarried out by the zoom system, for displacing the scanner system alongthe optical axis of the zoom system in a synchronized manner with thezoom setting of the zoom system, and adapt a position of the scannersystem, with respect to a current position of the virtual entry pupil ofthe zoom system, for continuously maintaining a value of distance of thescanner system from the virtual entry pupil of the zoom system.